NAA Hydraulic Lift

I got the lift cover off now and found nothing bent or twisted but the linkage is pretty sloppy due to wear I guess. I did see about .030 in. wear on the follower pin and more importantly, I found the pin was riding only half way on the cam surface causing that half of the cam surface to be worn over .060 in.
I then cut a 5/16 drill bit about 3/16 in. longer than the original pin and pressed that into place so that it now extends across the whole width of the cam surface. I had replaced the original pin several years ago and did not notice the cam wear. I will bet this alone will cause my lift to go all the way up,(my only problem) something is telling the control to stop pressurizing the piston and I bet it is these worn parts.
The two linkage adjustments are another matter! I have 2 ITT manuals and the one shows a plate over the valve to measure from, and the other manual shows the plate was dropped in the newer models. In any case, the control rod is way too far out and I am afraid to make the adjustments and the control valve turnbuckle would run out of thread before it met the spec. in either draft or position setting. For instance, the spec. is 3/16 in. in draft and it is running about 1/2 in. On position setting, the spec. is 1/4 in. and it measures about 5/8 in.

I have lengthened that rod to get it close, it does not have to be dead on, but the closer the better

I ran into the same problem. I made a longer plunger rod on my lathe out of some mild steel 7/16th hex stock tapped 1/4-28. I believe I added about .375 to the length of the hexagonal portion of the rod. It worked well.

The original pin was not long enough to cover the entire width of the cam surface. When the cam gets worn you should add metal back to the worn part with a welder and then grind it smooth to match the curve of the non-worn section and continue to use the correct original length pin. If you simply use a longer pin to ride on the non-worn section then that area will wear down as well and you won't know how much you have to build it up once it starts having problems again.

Yes, the longer pin will cause the cam to wear eventually especially since it rides on a smaller unworn section. I don't want to take all the linkage apart since I am afraid I will cause other problems! I sure do not understand why the two adjustments recommended in the ITT manual are so far off. There again, I am afraid to monkey with them. The adjustment in the draft setting is easy to make but the adjustment in the position setting is extremely difficult to make due to the tightness of the adjusting bolt arrangement.
I bet that if I took out all the linkages, I would find several really worn parts.

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N tractor club dot com has a pdf that's good.
NAA-Hyd-Ctrl-Adjustment.pdf

Thanks for the web site, it is the best thing I have seen regarding how to adjust the hydraulic system..........

I downloaded the PDF referenced by Ozlander. It looks to be useful when I get to that stage of my project. I gather from Zane Sherman's (I think) site that the hydraulic systems between the NAA and the hundred series tractors are very similar.